Tension for sewing-machines.



PATENTED OCT. 30, 1906.

W. WILSON. TENSION FOR SEWING MACHINES.

APPLIOATIOH TILED KAY 29, 1906.

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PATBNTED 00m. 30, 1900.

w. WILSON. TENSION FOR SEWING MACHINES.

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11: NGRIIS PETIRS c UNITED STATES PATENT OFFICE.

WILLIAM WILSON, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO ,CAMPBELL-BOSWORTH MACHINERY COMPANY, OF PORTLAND,

MAINE, A CORPORATION OF MAINE.

TENSION FOR SEWING-MACHINES.

Specification of Letters Patent.

Patented Oct. :30, 1906.

Application filed May29, 1905. Serial No. 262,742.

To all whom it may concern.-

Be it known that I WILLIAMWILsoN, a citizen of the United States, residing at Boston,

in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Tensions for Sewing-Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an improvement in tensions for sewing-machines, and more particularly to tension devices employed between the take-up and the other stitch-forming instrumentalities in order to prevent the existence of loose thread at the place of engagement therewith of the stitchiorming instrumentalities. "In the well-known Campbell sewing-machine the thread after passing from the pulloff passes around the thread-trucks, which constitute the take-up, thence down through a thread-tube to the looper, thread-finger, needle, and work. At a certain time in the operation of the machine when the take-up has completed its taking-up movement and released. its pressure upon the thread there is considerable slack thread in themachine between the thread-clamp on the supply side of the take-up and the work, and this slack thread ifp'ermitted to extend to the looper and thread-finger is liable to cause defective work by the slipping of the thread off of the thread-finger, which usually results in the breaking of the thread or by such a slackness in the-thread between the thread-finger and the looper as to prevent the proper laying of the thread in the hook of the needle, which sometimes causes the skipping of stitches or the stranding of the thread. In order to prevent such defective operation, it has been the practice to provide; the Campbell machineflwith a light tensiori'at the upper end of the thread-tube, which consisted of a piece of wire having its two ends extending outwardly over the tube upon opposite sides of the thread. The middle of the wire was held by the screw which secured the thread-tube in the machine. This wire is apparently shown in the-drawings of the patent-to Amborn, Jr., No. 388,752, August28, 1888; but it is not described in the specification. The objection to this form of a tension device resides in the fact that'it was uncertain in operation and diflicult in adjustment. It has long been the practice for operatives to tie pieces of thread around the two wires in order to hold them in the proper relation to each other and to bend the wire with the fin gers to afford the proper degree of tension upon the thread. It is apparent that such expedients are costly of the time of the operative and decrease the efficiency of the machine. Y

The object of the present invention-is to reorganize and improve this tension device in order to render it capable of ready adj ustment to various sizes of thread and kinds of wax or-gums used thereon and in a form which will readily clear itself of accumulations of wax or gum. I

To this end the present invention consists of the tension device hereinafter described, and particularly defined in the claims.

' In the accompanying drawings, Figure 1 is a side elevation of a portion of the Campbell sewing-machine. Fig. 2 is a sectional elevationof the thread tube and tension device. Fig. 3 is a plan of the same. Fig. 18 a section, taken at right angles to the'section of .Fig. 2; and Fig. 5 is a front view lookingfrom the left of Fig. 1 of the stitch-forming instrumentalities, showing their relation to the thread with the parts in the positions which they occupy in Fig. -1.

The'jthread-trucks D and E comprise the take-up hf the machine'and are constructed and operated substantially as described in l the patent to Campbell, No. 374,936, December 20, 1887. Frorimthe thread-truck E the thread extends through the tension device T, the thread-tube t to the looper L,a'nd thence to the work. The awl A, the thread finger F, the needle N, the shuttle S are all constructed and operated substantially as described in the patent to Campbell, No. 253,156, January 31, 1882' After the needle has descended, drawin a loop of the needlethread down through tl ie materials, the shuttle S advances and opens the loop of thread just drawn down by the needli nd passes therethrough. Then the take-up rises and exerts a pullupon the needle-thread, drawing the shuttle-loop back into the needle-hole and setting the stitch, after which the takeup moves to the position shown in Fig. 1, thereby slackening the thread, and simultaneously therewith the looper presents the thread to the thread-finger F, which moves rearwardly, and then to the hook of the needle, and the parts assume the position illustrated in Fig. 1, the tension upon the thread during these movements of the looper and thread-finger being that exerted by the tension T, which prevents the slackgiven up by the take-up from falling through the thread-tube and interfering with the proper operation of these parts.

The tension T consists of a piece of wire bent to form a circle and having its ends then bent diametrically across the circle, as seen in Fig. 3.. The circular portion 1 of the wire is embraced by a recess 2 in the upper end of the thread-tube 3. The circular portion 1 may be compressed to slip it into the recess 2. The two ends 4 4 of the piece of wire extend parallel to each other diametrically across the circular portion 1 and across the center of the thread-tube 3. Between these two thread-engaging portions of wire 4 the thread extends, and such portions 4 press lightly upon the opposite sides of the thread with sufiicient pressure to prevent the slack in the thread produced by the relaxation of the take-up from falling through the tube to the stitch-forming instrumentalities at the lower end thereof. It is not intended that the portions 4 of the wire should exert any considerable pressure upon the thread, it being sufiicient if they exert enough pressure to prevent the falling of the thread through the tube in the objectionable manner above referred to.

An adjusting-screw 5, screw-threaded through the ear 6, projected laterally from one side of the upper end of the thread-tube 3, enters the recess 2 and engages one side of the circularportion 1 of the wire. By turning the screw the circular portion may be expanded or contracted, and thus the portions 4 of the wire are moved toward or from each other to adjust them to their proper position with relation to the thread. A set-nut 7 is providedto secure the adjusting-screw 5 in its correct position. The recess 2 retains the circular portion 1 of wire throughout a considerable range of adjustment. Within the limits of the usual adjustment of the tension the movements of the thread-engaging portions 4 toward and from each other are nearly enough parallel for all practical purposes.

It is to be understood that adjustment of the tension is required to cause it to engage threads of larger or smaller sizes with the proper degree of pressure and that with wax or gums adjustment may be further required to adapt the tension properly to hold the thread.

It will be noted that the wires will freely clear themselves of accumulations of wax or gum and that it is a'very simple matter to remove the spring altogether and replace it with a new one in case of wear or accumulations of wax or gum.

The recess 2 is not continuous throughout the whole circumference of the tube, but, as shown in the drawings, for convenience in inserting and removing the tension-springs is made to extend around portions only of the tube: It is not material to the invention, viewed in its broader aspects, what portion of the circumference of the recess be omitted, except that sufiicient must be retained in order to hold the spring in position. It is preferred that the recess upon the adjustingscrew side of the spring extend throughout the whole half-circle, so that movements of the spring will not disengage the spring from the recess. This form of lip is illustrated in Fig. 3. It will be seen that the movements of the rear part of the half of circular portion 1 engaged by the set-screw toward. and from the other half of such circular portion will not disengage it from the portion of the recess engaging it.

What is claimed is- 1. A sewing-machine, having, in combination, a needle, a looper, a thread-finger, a take-up, and a thread-tube extending from the take-up to the needle-looper and thread finger, the upper end of the thread-tube being provided with a tension device consisting of two wires adapted to engage the opposite sides of the thread, and means for adjusting the position of the wires with relation to each other, substantially as described.

2. A sewing-machine, having, in combination, stitch-forming mechanism, a take-up, a thread-tube extending from the take-up to the stitch-forming mechanism, and a tension device located at the upper end of the threadtube to prevent the slack thread taken up by the take-up from dropping therethrough, consisting of a loop of wire with its ends bent parallel to each other across the loop, substantially as described.

3. A sewing-machine, having, in combination, stitch-forming mechanism, a take-up, a tension device located between the stitchforming mechanism and the takeup, consisting of a circular portion of wire having its ends extended diametrically thereacross and substantially parallel to each other, substantially as described.

4. A sewing-machine, having, in combination, stitch-forming mechanism, a take-up, and a tension device located between the take-up and the stitch-forming mechanism, consisting of a circular portion of wire having its ends bent diametrically across such circu-' sisting of a recessed member to receive the IO lar portion, and means for adjusting the discircular portion of the Wire, substantially as tance between the wire ends, substantially as I described.

described. I In testimony whereof I aflix my signature 5. A sewing-machine, having, in combinain presence of two witnesses.

tion, stitch-forming mechanism, and a ten- WILLIAM WILSON.

sion consisting of a circular portion of wire Witnesses:

having {its ends bent diametrically there- HORACE VAN EVEREN,

across, means for supporting the tension con- ALFRED H. HILDRETH. 

